Study On The Relationship Between P2X Purinergic Receptor Subtypes And Detrusor Instability

Background: Detrusor instability is one of the most common micturation dyfunction in urology cilinical experience, but the etiology remains unknown, and the effect of therapy is poor. Evidences were accumulated in both normal and functionally disturbed bladder, which purinergic receptors also involved in detrusor contraction besides muscarinic receptors playing an important role. But the concrete modulation mechanisms of the purinergic receptors is unestablished.In this investigation, the relationship between P2X pureinergic receptor and DI was explored by observing altered expression of P2X receptor subtypes in the control and instable detrusor of rat.Materials and methods: Bladder outlet obstruction was created in female Wistar rats by ligating the proximal urethra in the perineum for 6 weeks. Cystometries were performed in conscious rats 7 days after suprapubic bladder catheter implantation. The bladder capacity and pressure was measured and the incidence of detrusor instability was counted. The alterative frequency of spontaneous contraction of isolated control and instable detrusor strips undergo the modulation of ATP were studied. The mRNA was extracted from the detrusor of control and DI rats, and the expression of P2X receptor subtypes were detected by means of Reverse Transcriptive Polymerase Chain Reaction (RT-PCR). The different mRNA expressions of P2X receptor subtypes were identified.Results: Reflex micturition remained in conscious rats during in vivo cystometric evaluation. There were 76.67% obstructed rats developed DI. Bladder pressure and capacity remained normal in control rats, while significantly increased with high compliance in DI rats. Detrusor strips produced spontaneous contraction under a certain preload, and the frequency significantly increased in DI compare with control. ATP elevated the contraction frequency of both control and DI detrusor strips, with a greater alterative range of DI. ATP can also influence the contraction tension of the detrusor strips, but without statisticdifference. Six P2X receptor subtypes, except P2X6, can be detected in detrusor. P2X1, P2X5, P2X7 were significantly decreased, whereas P2X2 and P2X4 significantly increased in DI detrusor (p<0.01). The difference of P2X 3 was not detected.Conclusion: 1. DI model of rats was successfully established by proximal urethra ligating. Bladder pressure and capacity were significantly increased in DI rats. 2. The spontaneous contraction frequency was elevated in DI detrusor, indicated the enhanced excitability of DI. 3. ATP can increase the excitability of detrusor, the alterative ranges of DI was greater than that of control. 4. The differentia of P2X receptor subtypes expression of DI and control may offer a unique role in the modulation of detrusor activities.